Various types of envelope stuffing apparatus are well known. Earlier methods of envelope stuffing apparatus included a ram for stuffing enclosures into awaiting envelopes. See, for example, U.S. Pat. Nos. 4,443,007, 4,337,609 and 4,379,383. Alternate methods include biased belts for stuffing enclosures into an opened envelopes. See, for example, U.S. Pat. Nos. 4,888,938 and 5,191,751. As the throughput of inserting machines has increased the speed and reliability of the envelope stuffing apparatus has become more critical.
More recent methods of envelope stuffing apparatus have attempted to improve the speed and reliability of the inserting operation. For example, U.S. patent application Ser. No. 07/608,515, filed Nov. 2, 1990, discloses an envelope stuffing apparatus including coplanar first and second pusher means for transporting enclosures into an envelope.
Another example of an envelope stuffing apparatus is disclosed in U.S. Pat. No. 5,125,214. The apparatus includes a gripper drum for delivering envelopes to the inserting location, vacuum means for holding the bottom surface of the envelope as suction cups lift the top surface, and drop rollers for urging the stuffed envelope out of the inserting location. There is an insert pusher that retracts downwardly and backwardly out of the way of envelopes and enclosures being provided to the inserting location.
A further example is U.S. Pat. 4,674,258 which discloses an envelope stuffing apparatus in which enclosures are inserted by upper and lower belts and envelopes are transported to the inserting location by suction belts.
Finally, a complex insertion station is disclosed in U.S. Pat. No. 4,922,689 which includes a linearly reciprocating carriage that carries a plurality of pusher fingers.
It is an object of the present invention to provide an apparatus and method that simplifies the insertion process while increasing both the throughput and the reliability of the insertion station.